Since, in the processing of strip, lengths of different width may be joined together, it is known to sever such strip transverse to its length, i.e. to establish the finished length of strip or to effect such separation. The strip can also be trimmed, i.e. cut or slit in the longitudinal direction for finishing the lateral edges thereof and establishing the desired width thereof. The method and apparatus are particularly applicable to metallic strips, and substantially continuous strip treatments.
For example, in continuous treatment operations or processing lines for metallic strip, e.g. in pickling operations, annealing lines, coating operations and the like, the velocity of strip must be adapted to the particular process conditions for a given result. It is usually also desirable to maintain a constant velocity for the processing operations or unit operations thereof.
Accordingly, each part of the respective treatment line is customarily preceded by an inlet storage device. It can also be associated with an exit storage device. The storage devices serve to provide take-up capacity at the inlet and outlet members in response to the periods of interruption of advance of the strip as can arise, for example, during endwise joining of strip, or during severing or similarly slitting or cutting of the strip. Without such storage units, the line can generally not achieve a substantially constant velocity or interrupted operation in the parts between the storage units.
The strip is usually cut to the desired or finished length at the respective exit or outlet member, and this can be accompanied by lateral slitting (trimming) of the longitudinal edges of the strip to attain the desired width thereof.
The finished length of a strip can be obtained by way of a transverse shear or similar cutter wherein the blade or knife is disposed perpendicularly with respect to the longitudinal extent of the strip. The lateral slitting, to form the finished lateral edges, is done, in turn, with a device having adjustable knives or shears, which can be respectively brought into the operating position on each side of the strip and by means of which the ultimately desired width of the strip can be produced. Usually, the clippings or scraps obtained during the trimming of the edges are further handled by coilers or choppers.
In known lines of this type, the device for the lateral finishing or trimming of the strip is normally arranged at a distance from quite close to the transverse shear, or can be positioned more remote from the transverse shear. Because such processing lines need to process strip products with widely varying widths, it has been necessary heretofore to use a lateral stamping apparatus or like punch or press. The stamping apparatus is used to cut access openings at the joints of the continuously passing strip. The lateral slitting devices are then able to be brought into the position required at the strip when a change in the trimming width occurs.
Accordingly, each time the width of a strip is changed, by cutting off the junction between a leading length and a trailing strip or simply an operation of the lateral slitter device to allow such a change, there arises an associated period of interruption at the exit of the treating operation. During such downtime period, the following steps are carried out:
adjusting the lateral stamping apparatus to the desired strip width;
stamping respective shapes or cutouts from the strip at opposite sides thereof;
retracting the stamping apparatus on completion of the cuts;
advancing the strip until the resulting cutouts reach the lateral slitters;
adjusting the spacing of the lateral slitters;
preliminary cutting of the ne strip width;
confirming the actual cut by measurements; and
readjusting the lateral slitters, in conformity with the determined dimensions, as may be required.
During this period of interruption in advance of the strip from the exit side of the processing line to the coiler, the storage unit is accumulating strip in accordance with the prevailing strip velocity in the processing line. Subsequently, the joint portion, i.e. the section of the strip at which a welded or otherwise provided connection combines two lengths of strip in endwise relationship, is advanced to the transverse shear.
The strip is then cut such that the joint portion is cut-off by the transverse shear making two separate cuts; the first to establish the end of the leading length on a previous coil, and the second to establish the forward end or leading edge of the next or trailing strip for the next coil. The cut strip is then passed over guide rollers to a coilere spool or mandrel.
The time required for replacing a coil once the transverse cuts through the metal strip have been made is generally up to about 1.5 minutes. In this period, is included the removal of the previous coil, from the coiler and connecting of the oncoming length to form the next coil. In the known assemblies comprised of lateral splitters, subsequent transverse shear, the coiler, the periods of downtime at the lateral splitters have to be added to the replacement time for the coils. This leads to the need for large storage capacity for the strip at the exit member. Furthermore, in this arrangement it is assumed that the length of the strip is sufficient so that it will be feasible, at the selected strip velocity, to fill and empty the storage component without shutting down the associated operation or unit.
However, the length of a strip with a thickness of greater than 2 mm is normally too short to accommodate the downtime in the exit member. Furthermore, the velocity of the line and the particular strip velocity can be lowered at will, due to potential damages to the strip in the particular operation. For example, in a picking line, the strip may be subjected to excessive pickling on stopping in the solution at the pickling station, and the resultant product may not pass inspection and may be lost as reject material.